1. Field of the Invention
This invention relates to a positioning device, and more particularly, to an automatically leveling cradle for use in aligning a workpiece such as a cylinder head to be machined.
2. Description of the Related Art
The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is "prior art" with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. .sctn.1.56(a) exists.
U.S. Pat. No. 4,729,129, entitled "Machining Apparatus And Workpiece Holding Assembly Therefor", issued Mar. 8, 1988 to Elsdoerfer, is directed to a computer controlled machining apparatus which is capable of rotating the workpiece about one axis. No sensor is used to provide feedback to a microprocessor.
U.S. Pat. No. 4,607,578, entitled "Positioning Mechanism", issued Aug. 26, 1986 to Inoue, is directed to a device which provides six degrees of freedom, including linear movement along each of three mutually perpendicular axes, and rotational movement about each of these three axes. This device does not disclose attaching a sensor to the actual work piece and using this to align the work piece with a predetermined plane.
U.S. Pat. No. 4,127,942, entitled "Method And Apparatus For Reconditioning Cylinder Heads", issued Dec. 5, 1978 to Flaten, is directed to a device which uses a spirit guide for alignment purposes. This device does not disclose using a computer in combination with a sensor to provide alignment information to the computer to control the motors which rotate the cradle.
U.S. Pat. No. 3,782,847, entitled "Method and Apparatus For Reconditioning Cylinder Heads", issued Jan. 1, 1974 to Kulzer, is directed to another manual alignment device.